The invention relates to an electrical cabinet for accommodating electrical and/or electronic and/or optoelectronic installations, which is suitable in particular for installation outdoors and comprises an inner box and an outer box. A weak-current distribution installation may be, for example, a telephone installation having associated power supply devices and outgoing and incoming cable connection devices for a specific physical area.
Such electrical cabinets need to satisfy various conditions. Firstly, they should protect the electrical or electronic components of the installation against mechanical influences. In addition, the electrical cabinets should provide the operating conditions for the electrical and electronic or optoelectronic installations in the interior of the inner box which are required for fault-free operation.
It is firstly necessary to protect the installations against external influences, such as dust, moisture or vermin. The inner box is therefore well sealed off from the environment during operation. In order to ensure electromagnetic compatibility (EMC), the inner box generally has a metallic casing, which likewise requires a conductive seal with virtually no gaps. The electrical, electronic and/or optoelectronic installations generate heat during operation. This heat needs to be dissipated from the inner box in order to avoid overheating of the installations. An air flow is generally formed in the interior of the inner box, in the case of which warm air rises upwards. Owing to the air flow forming in the interior of the inner box, the heat is at least partially guided towards the peripheral faces of the inner box. At least part of the generated heat can be dissipated via said peripheral faces.
EP 1 002 352 B1 has disclosed a generic electrical cabinet, in which an intermediate space is formed between an inner box and an outer box. The electrical cabinet is designed such that air can flow into the intermediate space from below, is heated at the peripheral faces of the inner box and as a result rises and exits again in an upper region of the electrical cabinet through exit openings in the outer box. Owing to the air circulation in the intermediate space between the inner box and the outer box, the peripheral faces of the inner box are cooled and therefore the heat generated by the electrical installations in the inner box is dissipated from the electrical cabinet.
In this case, the intermediate space between the inner box and side walls of the outer box is delimited at the top by an intermediate lid. Active elements, for example fans, are arranged in openings in the inter-mediate lid, with the result that cold air is sucked in through the essentially vertical intermediate spaces between the inner box and the outer walls of the outer box, exits through the openings in the intermediate lid and is deflected laterally by an upper cover, which protrudes laterally beyond the side walls of the outer box, and is guided through a gap to the outside, which gap is formed between the upper cover, which protrudes beyond the side wall, and the side wall of the outer box.
Although the known electrical cabinets provide a certain amount of cooling of the peripheral faces of the inner box and thereby cooling of the interior of the inner box, electrical cabinets with improved cooling performance are required in order to be used, in particular, in areas which have a particularly unfavorable climate and have a particularly high degree of insulation or a particularly high ambient air temperature.